1. Field of the Invention
The present invention relates to an exchange apparatus for exchanging data between an asynchronous transfer mode network and an Internet protocol communication network.
2. Description of the Related Art
In recent years, as Internet is growing, the scale and area thereof are drastically becoming large and affect the architecture thereof not a little. Particularly, with respect to a fundamental protocol of Internet (referred to as Internet protocol (IP)), such a drastic growth results in many problems for example shortage of addresses, tremendous increase of path information, and expandability of functions to new fields.
To solve such problems, the Internet Community has evaluated the next generation Internet protocol IPv6 against the current Internet protocol IPv4. The Internet protocol IPv6 is a datagram type communication protocol. The Internet protocol IPv6 has a path control function as a basic function. The Internet protocol IPv6 corresponds to a network layer of a protocol stack and is a fundamental protocol of Internet.
The Internet protocol IPv6 has been technically evaluated in IETF (Internet Engineering Task Force) that is an open committee of the Internet. The results evaluated in IETF are published to the Internet community as systems called RFC (Request For Comments) and Internet Draft that are official documents on Internet. As actual evaluation items of the Internet protocol IPv6, there are (1) expansion of address space from 32 bits to 128 bits, (2) simplified process due to simplification of header format, (3) easiness of functional expansion and enhancement of security function with expanded header, (4) functions corresponding to new services such as mobile host, multi-cast communication, real-time communication, and play & plug, and (5) easy upgrade from IPv4 to IPv6.
FIG. 13 shows a conventional packet format of data transferred in asynchronous transfer mode (ATM). Packet data 100' in an ATM network is composed of an address portion 101' and an information portion 102'. The address portion 101' stores information that represents a transfer destination as represented by "abc". The information portion 102' stores main information to be transferred. In other words, with reference to the transfer destination information stored in the address portion 101', the packet data 100' is successively transferred. Thus, information stored in the information portion 102' can be transferred to the desired transfer destination.
FIG. 14 shows the structure of an ATM network. FIG. 14 shows connections of remote networks and nodes. Remote networks 201' and 202' are connected to an ATM node 301' disposed at the vertex of a plurality of ATM nodes 301' to 307' in a tree shape. When the packet data 100' shown in FIG. 13 is transferred, the ATM nodes 301' to 307' recognize the address information "abc" in the address portion 101' of the packet data 100' and transfers the packet data 100' to the transfer destination corresponding to the address information "abc".
To widely use a network, an ATM network and a network corresponding to the Internet protocol (hereinafter referred to as IP network) may be connected. To connect the ATM network and the IP network and transfer a datagram of the IP network (hereinafter referred to as IP datagram) in the ATM network, the address in the ATM network (hereinafter referred to as ATM address) and the address in the IP network (hereinafter referred to as IP address) should be correlated.
To do that, an address table having ATM addresses and IP addresses corresponding thereto is provided. With reference to the table data, an address is converted between the ATM network and the IP network. Thus, a desired IP datagram is transferred. In this case, to allow a transfer destination router to transfer an IP datagram, the transfer destination router should know the location of the receiving party. Consequently, all routers should have table information of all paths from a particular transfer destination to a final transfer destination.
However, in a conventional address converting apparatus, to transfer an IP datagram between an ATM network and an IP network that have different protocols, an ATM address should be solved (obtained) from an IP address. Thus, the following problems take place.
In other words, to solve (obtain) an address in the ATM network or route an IP datagram, the Internet protocol should be assembled with an ATM cell. In other words, an address of the IP network should be solved (obtained) in the Internet protocol layer. In addition, since table information that correlates ATM addresses and IP addresses of all users is required, an address converting apparatus such as an IP-ATM connecting exchange apparatus requires a memory or an external storing unit that stores table information that correlates ATM addresses and IP addresses of all users.
Only with address information of a communication party, since the location of an address converting apparatus such as an IP-ATM exchange apparatus and an IP-ATM connecting exchange apparatus as a transfer destination cannot be obtained, thus, all address converting apparatuses should have table information that represents connection paths among other IP-ATM exchange apparatuses and IP-ATM connecting exchange apparatuses. In addition, to identify a communication quality requested by a user and a communication group, a special communication procedure or a special protocol is required. Alternatively, the network side should register users. However, it is very difficult to identify a communication quality requested by a user, provide a proper path and a proper bandwidth for transferring an IP datagram, and identify a CUG (Closed Users Group) of a user for selecting a proper communication party and transferring an IP datagram thereto.
However, in a capsulization such as Internet engineering task force RFC1483 of the Internet protocol IPv6, an address assignment for an ATM network is not considered. An interface between an IP network and an ATM network and new routing services (such as QoS) have not been accomplished. Thus, in the Internet protocol IPv6, there are problems with respect to the IP network and ATM network as with the Internet protocol IPv4. When an IP datagram is transferred, the service quality, bandwidth, real time communication, and so forth are not assured. In particular, in the IP network, when the next address of a particular address is a domain name used in a far country, a routing process becomes complicated.